by Dr Justin Marley

Blog Review: Evolutionary Psychiatry

The blog reviewed here is the Evolutionary Psychiatry blog by Dr Emily Deans MD. This is a blogspot blog. The articles feature on the central pane which is light brown on a beige ‘faded world map’ background. Articles are titled, dated, tagged and identify backlinks. The articles feature text with hypertext links where appropriate. On the right side of the screen are links to the About section, similar blogs, followers and a chronological index of posts. At the time of writing there are 88 posts. In the About section, Deans writes that

‘I’m a psychiatrist in Massachusetts searching for evolutionary solutions to the general and mental health problems of the 21st century’

She writes further in the introductory post about the paleolithic period as one in which she will find these solutions. This is a period spanning some 2.5 million years which utilised stone tool technology and which has given rise to the so-called paleolithic diet. The basic premise is expanded on in this post in which Deans writes that

‘Anthropological evidence and epidemiological studies of modern and past hunter gatherers, as well as agrarian societies of the last 10,000 years, show us that the physical health of hunter gatherers far surpasses the health of grain-based societies‘

However this can be contested on multiple grounds. Fauna has changed considerably over terrain and time periods. Agriculture was a feature of Ancient Egypt and yet a recent study provided evidence of reduced risk of cancer in this civilisation although longevity may have been diminished relative to life expectancy in many countries today (I think there was almost certainly a selection bias in the sample set in terms of representation of the society). Additionally Homo Neanderthalensis specimens are found with evidence of multiple pathology and diminished lifespan compared to modern life expectancy. Thus the term ‘physical health’ is rather broad and could be more usefully tightly defined. However the choice of the paleolithic period both here and in the wider background literature is one in which I don’t think simple assumptions can be derived. If we talk about stone tool technology then there are many primates today that have been found to use such technology including chimpanzees (that can properly be considered as omnivores). If our common ancestors were also capable of using such tools then the paleolithic period could be extended by some several million years. Even here the tool use of Capuchin monkeys in South America could extend this even further by tens of millions of years (although a critic may counter that such tool use may represent the very gradual development of a culture over this time period and that this might not therefore be relevant to our concestors). More recent debates have focused not on the importance of grain or tool use but instead on cooking as a key turning point in the evolution of the hominid brain because of the high energy use of the brain and the energy/efficiency advantages that cooking confers.

Even though the above suggests that the central assumptions are far from straightforward, Deans goes on to provide the reader with fascinating anthropological insights into diet. In this post for instance Deans draws attention to the diet of the Kitavans in Papua New Guinea and a reduction in prevalence in various diseases. There’s also this post examining links between depression and diabetes which I suspect is a very useful way to be able to make evolutionary links. The posts are quite detailed and Deans looks at the research, carefully explaining the background for readers unfamiliar with the nuances of the subjects under discussion. In some posts, Deans polarises the issues which I think makes them more accessible to the general reader. One example is this post on the benefits of zinc supplementation in depression. However I think that these matters are never straightforward (my dysfunctional assumption perhaps!). This paper for instance summarises research in this area. Although there is an impressive amount of data supporting the hypothesis, the authors write that

‘However, another study in an aging European sample found no association between mood and zinc status; zinc status was within the normal range, which suggests that the potential influence of zinc on mood may be small and undetectable when zinc status is within normal limits‘

There are also a few posts discussing the possible relationship between diet and Alzheimer’s Disease such as this one. Deans has a very good grasp of biochemistry and is versatile in interpreting the research literature. She also uses a simple hypothesis – that dietary grain is bad for health. A simple hypothesis can also be a prejudice and this is both an advantage and disadvantage. The advantage of this approach is that Deans can refine her understanding of this relationship with time and work on assumptions further downstream – in effect developing a theory as a collection of hypotheses. However, the disadvantage is that this assumption may prove incorrect which would have implications for the subsequent ‘downstream’ work and as discussed above the validity of this hypothesis is far from clear cut. There is another element to Dean’s writing however and that is the biocchemical approach to mental illness. I don’t think this is by itself the right level of analysis to provide a complete answer to the questions posed but the specialised knowledge that is demonstrated here can give very valuable insights into mental illness. The quote above (regarding zinc) illustrates the point that biochemical effects are likely to be small in terms of phenomenon as complex as mental illnesses and broader explanatory models are required on a theoretical basis. However this approach is very well suited in informing hypotheses for empirical testing where there may be a practical clinical benefit once the research has been conducted. Evolutionary psychiatry is developing significantly as is the understanding of human evolution and it will be interesting to follow developments on this blog.

Index: An index of the site can be found here. The page contains links to all of the articles in the blog in chronological order. Twitter: You can follow ‘The Amazing World of Psychiatry’ Twitter by clicking on this link. Podcast: You can listen to this post on Odiogo by clicking on this link (there may be a small delay between publishing of the blog article and the availability of the podcast). It is available for a limited period. TAWOP Channel: You can follow the TAWOP Channel on YouTube by clicking on this link. Responses: If you have any comments, you can leave them below or alternatively e-mail justinmarley17@yahoo.co.uk. Disclaimer: The comments made here represent the opinions of the author and do not represent the profession or any body/organisation. The comments made here are not meant as a source of medical advice and those seeking medical advice are advised to consult with their own doctor. The author is not responsible for the contents of any external sites that are linked to in this blog.